1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same.
2. Description of the Related Art
In JP2000-216373 A1, there is described a method for forming a MOS transistor on a semiconductor substrate. In the document, a gate electrode is formed on the substrate with interposed a gate insulating film therebetween. An LDD region is then formed by forming a first sidewall on each side surface of the gate electrode and using the gate electrode and the first sidewalls as a mask to implant ions into the substrate. Using the first sidewalls suppresses thermal diffusion of impurities introduced by the ion implantation into the substrate under the gate electrode, thereby reducing gate-drain capacitance. Further, a source and a drain are formed by forming a second sidewall on the exterior side surface of each of the first sidewalls and using the gate electrode and the first and second sidewalls as a mask to implant ions into the substrate. In JP2000-216373 A1, each of the first and second sidewalls is formed of an insulating film made of silicon oxide or silicon nitride.